First year CIS graduate student co-author on a Nature magazine cover article

Graduate

Astronomy and Space Science

About the cover: Simulated uniform curtain eruptions overlain on Cassini image N1637461416 adapted to make the erupted material visible. Images taken by the Cassini probe have revealed large fractures bounded by rifts towards the south pole of Saturn’s moon Enceladus. These features, popularly known as ‘tiger stripes’, reach higher temperatures than their surroundings and are thought to be the sources of observed jets of water vapour and icy particles. Joseph Spitale et al. compare Cassini images with simulated curtains of material erupting from Enceladus’ south-polar terrain to produce detailed maps of the emissions at various times. Much of the eruptive activity can be explained by broad, curtain-like eruptions, many of which were probably misinterpreted previously as discrete jets. Phantom jets in the synthesized curtains correspond closely to regions of enhanced brightness in the Cassini images. Cover: NASA/JPL-Caltech/Space Science Institute/Planetary Science Institute.

Publication abstract: Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called ‘tiger stripes’, named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles1, 2, 3, 4 and to exhibit higher temperatures than the surrounding terrain5, 6. Subsequent observations have focused on obtaining close-up imaging of this region to better characterize these emissions. Recent work7 examined those newer data sets and used triangulation of discrete jets3 to produce maps of jetting activity at various times. Here we show that much of the eruptive activity can be explained by broad, curtain-like eruptions. Optical illusions in the curtain eruptions resulting from a combination of viewing direction and local fracture geometry produce image features that were probably misinterpreted previously as discrete jets. We present maps of the total emission along the fractures, rather than just the jet-like component, for five times during an approximately one-year period in 2009 and 2010. An accurate picture of the style, timing and spatial distribution of the south-polar eruptions is crucial to evaluating theories for the mechanism controlling the eruptions.